1. Field of the Invention
The present invention relates to a beam let-off apparatus for adjusting the tension of a plurality of elastomeric filaments as they are removed from a beam and transported to a downstream operation.
2. Description of Background Art
Attempts to control the tension of a plurality of filaments as they are taken off a beam and led to a downstream knitting or weaving machine have taken a variety of forms. U.S. Pat. No. 5,259,421 discloses a complex system which uses a rack-and-pinion dancer roll positioned by a DC drive in response to a signal from a potentiometer output. Because of the high friction and low responsiveness of this design to filament tension, this apparatus is best suited to high-tension weaving of heavy fabrics, not to low-tension use of elastomeric filaments. U.S. Pat. No. 4,000,865 discloses another apparatus comprising a complex array of lever arms and air pressure regulators. U.S. Pat. NoS. 4,585,037 and 4,019,700 disclose the use of a tension roller and a dancer roll, respectively, as sensing devices, but the geometries of the apparatus require the use of expensive proportional control of motor speeds to control filament tension.
A simple, economical, and effective apparatus is still needed to let off spandex and other elastomeric filaments from a beam in preparation for knitting, weaving, and so on.